I have debugged the C code and everything works fine. I have also saved the various parameters passed to the C function to file to be sure that Fiddle was not passing some weird values, but there is no obvious (at least for me) problem.
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
double *mrt(
double *person_total_shortwave,
int rows_pts, int cols_pts,
double *dry_bulb_temperatures,
double *ground_temperatures,
double *atmospheric_longwave,
double *sky_view_factors,
double *shading_view_factors_matrix,
int rows_svf, int cols_svf,
double *shading_temperatures_matrix,
int rows_st, int cols_st,
int size_dbt,
double person_emissivity_shortwave, double person_emissivity_longwave,
double surroundings_emissivity, double ground_emissivity, double ground_person_view_factor);
int save_to_file(char *filename, int m, int n, double *mat)
{
FILE *fp;
int i, j;
if ((fp = freopen(filename, "w", stdout)) == NULL)
{
printf("Cannot open file.\n");
exit(1);
}
for (i = 0; i < m; i++)
for (j = 0; j < n; j++)
if (j == n - 1)
printf("%.17g \n", mat[i * n + j]);
else
printf("%.17g ", mat[i * n + j]);
fclose(fp);
return 0;
}
int main(void)
{
// REPLACE WITH C DATA FROM FILE
double *mrt_result;
mrt_result = mrt(person_total_shortwave[0],
rows_pts, cols_pts,
dry_bulb_temperatures,
ground_temperatures,
atmospheric_longwave,
sky_view_factors,
shading_view_factors_matrix[0],
rows_svf, cols_svf,
shading_temperatures_matrix[0],
rows_st, cols_st,
size_dbt,
person_emissivity_shortwave, person_emissivity_longwave,
surroundings_emissivity, ground_emissivity, ground_person_view_factor);
// save_to_file(rows_pts, cols_pts, mrt_result);
return 0;
}
// https://www.dropbox.com/s/ix06edrrctad421/Calculation%20of%20Mean%20Radiant%20Temperature3.odt?dl=0
double *mrt(
double *person_total_shortwave,
int rows_pts, int cols_pts,
double *dry_bulb_temperatures,
double *ground_temperatures,
double *atmospheric_longwave,
double *sky_view_factors,
double *shading_view_factors_matrix,
int rows_svf, int cols_svf,
double *shading_temperatures_matrix,
int rows_st, int cols_st,
int size_dbt,
double person_emissivity_shortwave, double person_emissivity_longwave,
double surroundings_emissivity, double ground_emissivity, double ground_person_view_factor)
{
save_to_file("PTS.txt", rows_pts, cols_pts, person_total_shortwave);
save_to_file("SVF.txt", 1, cols_svf, sky_view_factors);
save_to_file("SVSM.txt", rows_svf, cols_svf, shading_view_factors_matrix);
save_to_file("STM.txt", rows_st, cols_st, shading_temperatures_matrix);
double *mrt_mat = (double *)calloc(rows_pts * cols_pts, sizeof(double));
save_to_file("MRT_MAT0.txt", rows_pts, cols_pts, mrt_mat);
int t, c, k;
double sigma = 5.67E-8;
double body_area = 1.94;
double tmrt4_shortwave, tmrt4_longwave_ground, tmrt4_atm_longwave, tmrt4_surroundings;
double tmrt4_shading[rows_svf];
memset(tmrt4_shading, 0.0, rows_svf * sizeof(double));
double tmrt4;
double surroundings_view_factor;
// t runs through the timesteps
// c runs through the points in the mesh
for (t = 0; t < rows_pts; t++)
{
for (c = 0; c < cols_pts; c++)
{
tmrt4_shortwave = 1.0 / (sigma * body_area) * (person_emissivity_shortwave / person_emissivity_longwave) * person_total_shortwave[t * cols_pts + c];
// We are assuming that the ground is at ambient temperature
tmrt4_longwave_ground = ground_person_view_factor * ground_emissivity * pow((273.15 + ground_temperatures[t]), 4);
// Here we are using the actual long wave radiation from the sky
tmrt4_atm_longwave = (1.0 - ground_person_view_factor) / sigma * sky_view_factors[c] * atmospheric_longwave[t];
// We need to remove the contribution of all the shading devices
// k runs through the shading devices
surroundings_view_factor = 1.0 - sky_view_factors[c];
for (k = 0; k < rows_svf; k++)
{
surroundings_view_factor -= shading_view_factors_matrix[k * cols_svf + c];
}
tmrt4_surroundings = (1.0 - ground_person_view_factor) * surroundings_view_factor * surroundings_emissivity * pow((273.15 + dry_bulb_temperatures[t] - 0.0), 4);
// We now need to account for all contributions of the shading devices
for (k = 0; k < rows_svf; k++)
{
tmrt4_shading[k] = (1.0 - ground_person_view_factor) * (shading_view_factors_matrix[k * cols_svf + c]) * surroundings_emissivity * pow((273.15 + shading_temperatures_matrix[k * cols_svf + t]), 4);
}
// Finally we add them all (see paper) for the total contribution
tmrt4 = tmrt4_shortwave + tmrt4_longwave_ground + tmrt4_atm_longwave + tmrt4_surroundings;
for (k = 0; k < rows_svf; k++)
{
tmrt4 += tmrt4_shading[k];
}
// Just convert to celsius
mrt_mat[t * cols_pts + c] = pow(tmrt4, 0.25) - 273.15;
}
}
save_to_file("MRT_MAT.txt", rows_pts, cols_pts, mrt_mat);
// double x = 1.5;
// while (1)
// {
// x *= sin(x) / atan(x) * tanh(x) * sqrt(x);
// }
return mrt_mat;
}
require "fiddle"
require "fiddle/import"
module RG
extend Fiddle::Importer
@handler.handlers.each { |h| h.close unless h.close_enabled? } unless @handler.nil?
GC.start
dlload File.join("utils")
extern "double* mrt(double*, int, int, double*, double*, double*, double*, double*, int, int, double*, int, int, int, double, double, double, double, double)"
def self.mat_to_ptr(matrix)
return Fiddle::Pointer[matrix.flatten.pack("E*")]
end
def self.ptr_to_mat(ptr, rows, cols)
length = rows * cols * Fiddle::SIZEOF_DOUBLE
mat = ptr[0, length]
return mat.unpack("E*").each_slice(cols).to_a
end
def self.mean_radiant_temperature(
person_total_shortwave,
dry_bulb_temperatures,
ground_temperatures,
atmospheric_longwave,
sky_view_factors,
shading_view_factors_matrix,
shading_temperatures_matrix,
person_emissivity_shortwave,
person_emissivity_longwave,
surroundings_emissivity,
ground_emissivity,
ground_person_view_factor
)
rows_pts = person_total_shortwave.size
cols_pts = person_total_shortwave[0].size
person_total_shortwave_pointer = RG.mat_to_ptr(person_total_shortwave)
dry_bulb_temperatures_pointer = RG.mat_to_ptr(dry_bulb_temperatures)
ground_temperatures_pointer = RG.mat_to_ptr(ground_temperatures)
size_dbt = dry_bulb_temperatures.size
atmospheric_longwave_pointer = RG.mat_to_ptr(atmospheric_longwave)
sky_view_factors_pointer = RG.mat_to_ptr(sky_view_factors)
rows_svf = shading_view_factors_matrix.size
if rows_svf > 0
cols_svf = shading_view_factors_matrix[0].size
else
cols_svf = 0
end
shading_view_factors_matrix_pointer = RG.mat_to_ptr(shading_view_factors_matrix)
rows_st = shading_temperatures_matrix.size
if rows_st > 0
cols_st = shading_temperatures_matrix[0].size
else
cols_st = 0
end
shading_temperatures_matrix_pointer = RG.mat_to_ptr(shading_temperatures_matrix)
mrt_pointer = mrt(
person_total_shortwave_pointer,
rows_pts, cols_pts,
dry_bulb_temperatures_pointer,
ground_temperatures_pointer,
atmospheric_longwave_pointer,
sky_view_factors_pointer,
shading_view_factors_matrix_pointer,
rows_svf, cols_svf,
shading_temperatures_matrix_pointer,
rows_st, cols_st,
size_dbt,
person_emissivity_shortwave,
person_emissivity_longwave,
surroundings_emissivity,
ground_emissivity,
ground_person_view_factor
)
return RG.ptr_to_mat(mrt_pointer, rows_pts, cols_pts)
end
end
// REPLACE WITH RUBY DATA FROM FILE
mean_radiant_temperatures = RG.mean_radiant_temperature(
person_total_shortwave,
dry_bulb_temperatures,
ground_temperatures,
atmospheric_longwave,
sky_view_factors,
shading_view_factors_matrix,
shading_temperatures_matrix,
person_emissivity_shortwave,
person_emissivity_longwave,
surroundings_emissivity,
ground_emissivity,
ground_person_view_factor
)
File.open("MRT_MAT_RUBY.txt", "w") do |f|
mean_radiant_temperatures.each do |row|
f.puts row.join(' ')
end
end
I am quite familiar with Ruby, but C is not really my strength. It would be great being able to debug the C code when called from Ruby, but I don't really know how to do it.
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